On Wed, May 31, 2017 at 06:01:10PM -0700, Michel Thierry wrote:
> On 5/31/2017 12:05 PM, Chris Wilson wrote:
> >Commit 7c3f86b6dc51 ("drm/i915: Invalidate the guc ggtt TLB upon
> >insertion") added the restoration of the invalidation routine after the
> >GuC was disabled, but missed that the GuC was unconditionally disabled
> >when not used. This then overwrites the invalidate routine for the older
> >chipsets, causing havoc and breaking resume as the most obvious victim.
> >
> >We place the guard inside i915_ggtt_disable_guc() to be backport
> >friendly (the bug was introduced into v4.11) but it would be preferred
> >to be in more control over when this was guard (i.e. do not try and
> >teardown the data structures before we have enabled them). That should
> >be true with the reorganisation of the guc loaders.
> >
> >Reported-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> >Fixes: 7c3f86b6dc51 ("drm/i915: Invalidate the guc ggtt TLB upon insertion")
> >Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
> >Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> >Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
> >Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
> >Cc: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> >Cc: Arkadiusz Hiler <arkadiusz.hiler@xxxxxxxxx>
> >Cc: <stable@xxxxxxxxxxxxxxx> # v4.11+
> Reviewed-by: Michel Thierry <michel.thierry@xxxxxxxxx>
>
> btw the bug can only happen in 4.11; in 4.12+ this safeguard is
> already redundant since enable_guc_loading should be zero and
> ggtt_disable_guc is never called.
Thanks for the review, pushed so we can get it back to where it needs to
go. I'll send a patch to convert this to an assert in a moment.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre